⚡ update only look at previous facts iteration.

fol/kb.py

@@ -4,6 +4,10 @@ import fol
 class Kb:
     def __init__(self):
         self.base = []
+
+        self.prev = []
+        self.current = []
+
         self.indexes = {}
         self.counter = fol.cnf.Counter()
 
@@ -107,18 +111,22 @@ class Kb:
                     self.indexes[p.value] = [req]
         self.check_request(req)
         self.base.append(req)
+        self.current.append(req)
 
     def tell(self, request):
         req = self.make_f(request)
         self.add_req(req)
 
-    def ask(self, request):
+    def generate(self):
         while True:
-            n = len(self.base)
             self.update()
-            if n == len(self.base):
+            self.prev = [c for c in self.current]
+            self.current = []
+            if len(self.prev) == 0:
                 break
 
+    def ask(self, request):
+        self.generate()
         req = self.make_req(request)
         results = []
 
@@ -150,7 +158,12 @@ class Kb:
 
             facts = [f[0] for f in facts]
 
-            self.solve(rule, self.conds(rule), facts, solution, solutions)
+            rules = self.conds(rule)
+
+            if not self.is_rule_needed(rules, self.prev):
+                continue
+
+            self.solve(rule, rules, facts, solution, solutions)
 
             for sol in solutions:
                 concl = conclusion.subst(sol)
@@ -158,6 +171,14 @@ class Kb:
                     self.add_req([concl])
                     return
 
+    def is_rule_needed(self, rule, prev):
+        for f in prev:
+            for r in rule:
+                s = fol.unify(r, f[0])
+                if s is not None:
+                    return True
+        return False
+
     def merge_substs(self, substs):
         res = {}
         for s in substs:

sine_patre.py

@@ -14,6 +14,7 @@ if __name__ == '__main__':
             answer = kb.ask('Est(ALICE, x, y)')
 
             print(answer)
+            # [print(k) for k in kb.base]
 
             if False:
                 print(f'{len(kb.base)}----------------')